Float operated switch



April 1961 T. c. JOHNSON, SR 2,979,583

FLOAT OPERATED SWITCH Filed May 14, 1959 INVENTOR. T. c. JOHNSON, Sr.

ATTORNEY FLOAT OPERATED SWITCH Thaddeus C. Johnson, Sr., P.0. Box 525,Clinton, S.C. Filed May 14, 1959, Ser. No. 813,200

7 Claims. (Cl. 200-84) The present invention relates to float operatedswitches,

' and more particularly to a float operated mercury switch forcontrolling and protecting well pumps and the motors of pumps and thelike.

A primary object of the invention is to provide a float operated mercuryswitch which is highly simplified in construction, compact, reliable andefficient in operation,

, and economical to manufacture.

A further object of the invention is to provide a float operated switchwhich may be attached directly to the foot valve of a well pump orsuspended at the desired elevation in the well independently of the footvalve.

A further object is to provide a float operated mercury switch which isadapted to a wide variety of applications other than the preferredapplication or use of the switch in conjunction with a well pump andmotor.

Other objects and advantages of the invention will be apparent duringthe course of the following description.

In the accompanying drawings forming a part of this application and inwhich like numerals are employed to designate like parts throughout thesame,

Figure 1 is a central vertical longitudinal section through a floatoperated mercury switch according to the invention.

Figure 2 is an enlarged fragmentary central vertical section taken online 2-2 of Figure 1.

Figure 3 is a side elevation, partly diagrammatic, showing the floatoperated switch mounted upon the foot valve of a well pump.

Figure 4 is an electrical wiring diagram showing a possible circuitwhich includes the float operated switch.

Figure 5 is an enlarged fragmentary vertical section through a modifiedform of float operated mercury switch having a snap action device.

Figure 6 is a view similar to Figure 5 with the snap action device shownin the active position for compressing the bellows containing themercury.

Figure 7 is an enlarged fragmentary vertical section through a floatcheck valve at the bottom of the casing.

In the drawings, wherein for the purpose of illustration is shown apreferred embodiment of the invention, the

numeral 10 designates an elongated casing or cylinder formed of metal,plastics material or the like and having a bottom wall 11 provided witha central opening 12, Figure 7. The upper end of the cylinder 10 isformed open, and adjacent to such upper end the cylinder has an integralscrewthreaded external flange 13, as shown.

- The cylinder 10 is provided near and below its upper end with two ormore ports 14 for a purpose to be described.

A float check valve casing 12, Figure 7, is secured within the opening12 of bottom wall 11 by means of a lock nut 13' or the like. The checkvalve casing has a chamber 14 with a restricted opening 15 at its upperend and communicating with the interior of cylinder 10. A float ballcheck valve element 16 of lightweight material adapted to float in wateris arranged captively within the chamber 14, and an insert 17' withinthe lower tubular portion of the casing 12' has a plurality of spacedin- United States Patent 0 Patented Apr. 11, 1961 ternal ribs 18' whichengage the ball check valve element 16' to prevent it from falling outof the casing 12 but allow the passage of water through the casing 12'when the ball is engaging the ribs 18 as in Figure 7. When the ball 16'floats upwardly in the chamber 14 and engages the conical seat 19'afforded by the restricted opening 15', the ball will seal the opening15' so that water cannot flow through the casing 12.

A cap 15 of insulating material rests upon the upper end of the cylinder10 and has a reduced body portion 16 projecting downwardly into thecylinder and terminating adjacent the ports 14, as shown. The cap 15 hasan upper marginal flange 17 which engages the top of the screw-threadedflange 13 of cylinder 10. A resilient accordion-pleated bellows 18formed of insulating rubber-like material is provided within the upperportion of the cylinder 10, and this bellows has its lower end closed bya wall 19 formed integral therewith. The upper cylindrical neck portion20 of the bellows is firmly secured around the cylindrical body portion16 in any preferred manner, so as to form a fluid tight joint therewith.

The body portion 16 of cap 15 has a central opening 21 formed throughits lower end, communicating directly with the interior of bellows 18,which contains a body of mercury 22. Above the opening 21, the cap 15has an enlarged upwardly flaring cavity 23 extending through the top ofthe cap 15 and extending upon opposite sides of the opening 21 in twodirections, as shown in Figure 2. As shown in Figure 1, the cavity 23may have the same width as the opening 21 in the direction at rightangles to Figure 2. The diameter of the opening 21 is considerablysmaller than the internal diameter of the bellows 18, so that upwardcompression of the bellows for a slight amount will cause the mercury 22to rise rapidly through the opening 21 and enter the cavity 23.

Mounted upon the top of the insulating cap 15 and covering the cavity 23is a circular flat insulating plate 24, preferably of the same diameteras the flange 17. A metallic cylindrical shell or cover 25 for wires 26is mounted upon the insulating plate 24 and extends above the cylinder10 as shown in Figure 1. The shell 25 has an integral marginal flange 27at its lower end, preferably having the same diameter as the insulatingplate 24 and abutting the'latter. A tubular coupling nut 28 is providedfor rigidly connecting the flange 27, plate 24 and the flanges 17 and 13in abutting relation, Figure 2, and the nut 28 has screw-threadedengagement with cylinder flange 13. The top of nut 28 has an inwardlydirected annular flange 29 which engages the flange 27 in clampingrelation, as shown. A fluid tight connection is thus provided betweenthe insulating plate 24 and the flange 17.

A pair of spaced electrical terminals 30 are bodily mounted upon theinsulating plate 24 in alignment with the underlying cavity 23, and apair of depending switch contact elements 31 are electrically connectedwith the terminals 30 at the bottom side of the plate 24, as shown inthe drawings. The contact elements 31 are of strip-like formation, andproject downwardly in the recess 23 and have their lower endsterminating near the slightly above the reduced opening 21. The contactelements 31 preferably extend across a major portion of the width ofcavity 23 as shown clearly in Figure 1. The arrangement is such thatwhen the bellows 18 is compressed upwardly as in Figure 2, the mercury22 will rise through the opening 21 and bridge the contacts 31 near thebottom of the cavity 23, Figure 2.

An elongated cylindrical float 32 is disposed within the cylinder 10,below the bellows 18, and this float has a guided fit within thecylinder so that it may rise and fall with the water level in a well orthe like. The upper end of the float 32 is adapted to directly contactthe bottom were wall 19 of bellows 18 to compressthe'bellows as" thewater level rises. When the float moves downwardly as in Figure 1, itstop end becomes spaced from the bellows float switch contacts 31.

series withthe filament of pilot light bulb 53.

"that the contacts 31are no longer bridgedby th e mercury.

Figures 3and 4 of the drawings illustrate the use of the float operatedswitch in connection with a wellpump 33, having a motor 34 and the usualfoot valve 35,'located within the well bore 36, Figure 3. The wires 26leading well again-rises"sufiiciently,-the pump motor willl begin fromterminals 30 extend through an opening in the top wall of shell 25 andhave a fluid tight connection'with the shell at 37. Above the shell 25,the wiresjZfiQconstitute a two wire cable 38 having ajwater-p'roofsheathing of'rubber or the like. The cable 38 leads'upwar'dly to and iselectrically connected with pump'motor control means 39, Figure 3. 'Thecylinder 10 of the float operated switch is directly secured to the footvalve means 35, as at 49 in Figure 3. If preferred, the float-operatedswitch may be supported independently of the foot valve by suspendingthe same upon its water-proof cable 38 at the desired elevation.

As shown in Figure 4, the control circuit for the pump motor 34 maycomprise a fused disconnect switch, having switch contacts 41 and 42,connectable across a power line having wires 43 and 44. The contact 41is connected to operate and the pilot light bulb 53 will again be off.

With reference to the float check valve shown particularly in Figure 7,when the water level in the well is lowered and drops below the upperend of float cylinder 10, the pressure of the water inside of thecylinder 10 forces the ball check valve element 16' downwardly or awayfrom the seat 19', allowing the water level in the cylinder 10 to drop'approximately with the outer water level until the float-operated switchstops thepump in the manner previously described. This allows the waterlevel in the well to rise again, but as the water levels within andexteriorly of the cylinder 10 are substantially equalized, the floatball check valve element 16 rises and engages the conical seat 19' forsealing the passage 15. This prevents further water from entering thelower end of cylinder 10. When the water level of the well now rises tothe level of the ports 14, it will enter these ports 'and'quickly fillthe cylinder 10 for startingthe pump again.

The described arrangement furnishes a differential be- "tween'jthe pumpstopping and starting water levels in the well. This differential mayalso be varied by making "the cylinderlil longer or shorter. It isevident that in a through a wire 45 with terminals 46 of control box'39,

and a further wire 47 leads from the control box to one terminal of themotor 34 as at 48. The other terminal 49 of the pump motor is connectedthrough a wire 50 with terminals 51 of the'control box 39, and a wire 52leading from one of the terminals 51 is connected in series with thefilament of a pilot light bulb 53. Another wire 54 leads from the lightbulb filament to another terminal 55 of the control box 39, whichcontrol box has additional terminals 56 electrically connected as shown.The wires 26 of cable 38 leading from the float switch contacts 31 areelectrically connected with a pair of the terminals 5'1 and 56, as shownin Figure 4.

The float switch contacts 31 are thus connected in When the water levelin the well here 36 is above the elevation of the foot valve and floatoperated switch, the latter is entirely submerged and the water mayenter the ports 14 and fill the cylinder iii, causingthe fioat 32 torise and contact the bellows 18. This will compress the bellowsupwardly, Figure 2, and the mercury 22 will rise into the cavity. 23and'bridge the contacts 31. The disconnect switch 4142 is now closed andthe motor 34 is energiz'ed to operate the pump 33,and water is beingpumped from the well 36. Current flows from the wire 43 through thewires and 47to the electric motor 34, and from the motor through thewire to contact 51, and from this contact through one of the wires 26,and across the switch contacts 31 which are bridged by the mercury 22. aThe current now flows through the other wire 26 and through the contactsand 56 and a further wire 57 back to the other Wire 44 of the powerline. While the float switch contacts 31 are thus closed or in circuitwith the motor, the pilot light bulb 53 is off, and the operator knowsthat the water level in the well is adequatelyhigh to allow the pump torun without losing its prime or without damaging the pump or itselectric motor.

When the water level in the well 36 becomes lowered to a level where itis unsafe to continue pumping water, the float 32 will descend in thecylinder 10 until the float is free of the mercury tilled bellows 18,and the bellows will expand downwardly so that the mercury 22-will fallbelow the level of the cavity 23 and open the circuit through the Whenthis occurs, the pump motor 34 is shut oh, and current will now howthrough the filament ofthe pilot light bulb 53 to indicate that thewater level is'too low for safe pumping and that the"pump'has'bee'nshut-ofi. 'When the water level in the dug or bored welldue to its relatively greater diameter "this differential action abovedescribed need not be as great as for a smaller diameter drilled well.The desired differential is also governed to some extent by the flow ofthe well and the rate of pumping.

The feature of the float check valve at the bottom of j the cylinder 10isoptional and may be omitted in some cases, if preferred, and in suchcases, the opening 12 of bottom wall 11 will still be provided.

In Figures 5 and 6 there is shown a slight modification of the floatoperated switch for imparting to the same as quick or'snappy action; Tothis end, the top of the float 32 is rigidly connected with a verticalbellows-actuating pin 58, havinga head 53 for direct contact with thebottom Wall of bellows 18. The pin 58 carries a transverse extension 60,slidably connected with a pair of slotted links 61 having their outerends pivoted at 62 to the sidewall of cylinder 10. A coil spring 63 isconnected with one pivot 62 and with the'pin extension St for causingthe actuating pin 58 to move upwardly rapidly toward contact with thebellows, when the links 61 pass the horizontal dead center positionwhile the float is rising. When this occurs, the'bellows 18 willbe'compressed upwardly with 'a quicker snappy action, andthe switchcontacts 31 will f be bridged by theinercury 22'much more quickly thanwould" be the case where the bellows is compressed by t the naturalrising of the float 32without any snap action "means. All other parts ofthe float operated switch,

lfigures'S and 6, are identical in construction and operation to thecorresponding parts shown anddescribed in the prior form of theinvention, Figures 1 and 2. I

" When the water level in the well is falling, and the float 32 isdescending in 'thecylinder 10, Figures 5 and 6, the 'operating pin 58will move downwardly and disengage "the bellows with a snappy action,once the links 61 have moved by horizontal dead center. This willdisconnect or open the switch contacts 31with a quick action.

It is to be understood that the forms of the invention herewith shownand described are to be taken as preferred examples ofthe same, and thatvarious changes in the shape,;size and arrangement of parts may beresorted to,

j"without departing from the spirit of the invention or the scope of thesubjoined claims.

Having thus described my invention, 1'. claim: 1. 'A float operatedmercury switch comprising an elongated tubular body portion havingopening means near its upper and-lower ends, a cap element mounted uponthe upper end of the body portion and having a recess formed in its topand an opening communicating-with said recess and'extending. throughthebottom of said cap,

"a bellows secured to said cap and depending therefrom and having abottom wall, said bellows disposed within the upper portion of thetubular body portion and having its interior communicating with saidopening of the cap, a body of mercury within said bellows and adapted torise through said opening of the cap when the bellows is compressedupwardly, a float arranged within said body portion below the bellowsand adapted to rise and fall relative to the bellows and to compress thebellows upwardly while rising, a cover plate for the top of said capextending over said recess, a pair of electrical terminals secured tothe cover plate, a pair of electrical contacts connected with saidterminals and depending from the cover plate and disposed within saidrecess above the opening of the cap to be bridged by the mercury whenthe mercury rises through said opening of the cap, and wires connectedwith the leading from said terminals of the cover plate.

2. A float operated switch comprising an elongated cylinder having abottom wall provided with an opening, said cylinder having a sideopening near its upper end, a cap formed of insulating material mountedupon the upper end of said cylinder and having a recess in its top and acentral opening formed through its bottom communicating with saidrecess, a bellows dependingly secured to said cap within the upperportion of said cylinder and having a bottom wall, the interior of thebellows communicating with said opening of the cap, a body of conductingfluid within said bellows adapted to rise through said opening of thecap and to enter said recess when the bellows is compressed upwardly, afloat disposed within said cylinder below said bellows and adapted tocompress the bellows when rising, an insulating cover plate mounted uponsaid cap and covering the top of said recess, a pair of electricalterminals secured to said cover plate, a pair of contact'elementsconnected with said terminals and depending from the cover plate anddisposed within the recess of the cap and above the opening of the cap,wires connected with said terminals and extending above the cover plate,a cylindrical shell mounted upon said cover late and enclosing saidwires, and detachable clamping means connected with the upper end ofsaid cylinder and engaging said shell and serving to clamp the shellagainst the cover plate and to also clamp the cover plate to said capand the cap to the upper end of said cylinder.

3. A float operated switch comprising a tubular guide to be supportedvertically during use and having opening means near its upper end, meansforming a chamber for an electrical conducting fluid upon the top ofsaid tubular guide, a bellows containing a body of said conducting fluiddependingly secured to said means within the upper portion of thetubular guide and communicating with the chamber of said means, a floatmounted within the tubular guide below said bellows and adapted to movevertically and to contact the lower end of said bellows to compress thesame upwardly, switch contact means mounted upon said means andprojecting into said chamber for contact with the conducting fluid whensuch fluid rises into said chamber, conductor means connected with andleading from the switch contact means, and an upwardly closingfloatcheck valve for the lower end of the tubular guide to provide adifferential in the operation of poweroperated means to be controlled bythe float operated switch.

4. A float operated switch according to claim 3, wherein said tubularguide includes a bottom wall having an opening, and wherein said checkvalve comprises a sleeve secured within said opening and defining achamber having a restricted opening at its uper end communicating withthe interior of the tubular guide, said restricted opening forming atapered valve seat, a buoyant check valve element arranged within thechamber of said sleeve and adapted to float into sealing engagement withsaid tapered valve seat, and projection means on said sleeve engageablewith said check valve element to prevent the same from dropping out ofsaid sleeve and allowing the passage of fluid upwardly through saidsleeve and around the check valve element.

5 A float operated switch comprising, a generally vertical guide device,means forming a chamber mounted upon the guide device, a bellows mountedwithin the guide device and having its interior in communication withsaid chamber, a body of conducting fluid mounted within the bellows, afloat mounted within the guide device below the bellows and adapted tobear against the bellows to compress it when the float rises, a snapaction device connected with the float to move it in either directionwhen the snap action device is shifted past dead center, contactelements extending into said chamber, and conductors connected with thecontact elements.

6. A float operated switch comprising, a generally vertical guidedevice, means mounted upon the upper portion of the generally verticalguide device and having a chamber and a relatively large opening leadinginto the bottom of the chamber, a generally vertical bellows mountedwithin the upper portion of the generally vertical guide device andhaving its interior in communication with the relatively large opening,a generally vertical float mounted within the generally vertical guidedevice and serving to compress the generally vertical bellows when thefloat rises, a body of conducting fluid mounted within the bellows andadapted to be moved through said opening in the chamber upon the upwardmovement of the bellows and to move out of the chamber when the bellowsmoves downwardly, and spaced contacts arranged within the chamber to beelectrically connected by the body of conducting fluid when said bodymoves into the chamber.

7. A float operated switch comprising, a generally vertical guidedevice, a cap formed of insulating material mounted upon the upper endof the generally vertical guide device, said cap having a generallyvertical chamber and a relatively large opening leading into the bottomof the chamber, said cap including a lower reduced portion, a generallyvertical bellows having its lower end closed and its upper end open andreceiving the reduced extension and secured thereto, said bellowssurrounding said opening and being in communication therewith, a body ofconducting fluid held within the bellows and forced through therelatively large opening into the chamber when the bellows is verticallycompressed, at float arranged within the generally vertical guide deviceto engage and compress the bellows, spaced contacts arranged within thechamber, and means to mount the contacts upon the cap.

Hancock Nov. 30, 1954 Hinojosa Feb. 5, 1957

